Method for coating copper on wafer bonding area

Abstract

The invention relates to a method for coating copper on a bonding area of a wafer, which comprises the following steps of: cleaning and drying the wafer, sputtering a metal layer, pasting a first protective film on the front surface of a copper sheet, preparing slurry for metal bonding, and transferring the slurry to the bonding area of the wafer; transferring the wafer subjected to slurry transfer printing into a sintering jig, designing an air inlet and an air outlet in the sintering jig, accurately placing a copper sheet in a bonding area of the wafer by aligning the copper sheet and the wafer identification mark, and enabling the bonding area of the copper sheet to be attached to the front surface of the slurry, the distance between the copper sheets of the adjacent bonding areas of the wafer is controlled within the distance causing short circuit of the bonding areas of the wafer; sintering the wafer covered with the copper sheet; filling an epoxy resin material between the non-bonding area on the front surface of the wafer and the groove on the back surface of the copper sheet, and carrying out plastic packaging; and removing the first protective film, transferring the wafer into a wafer separator, separating the wafer into independent chip assemblies, and drying the independent chip assemblies. According to the invention, the yield, reliability and stability of the chip can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chip manufacturing, and specifically discloses a method for copper coating a wafer bonding area. Background Art

[0002] In one of the known solutions, such as CN106170856A, the solution uses a pre-coated sintering paste to the bonding copper sheet, and then to the chip bonding area, through a pressure sintering process to form a bond between the chip and the pin. This process has relatively strict requirements on the size of the chip bonding area. Due to the limitation of the glue coating process, it is not suitable for smaller bonding areas (usually less than 2mm×2mm), and there are problems such as copper sheet drift causing short circuits and inconvenient operation. In addition, for copper sheets with height differences, there is a problem of inconvenient glue coating.

[0003] In another known solution, such as TW202345248A, the solution adopts pre-coating on the copper sheet, and also adopts the pressure sintering process to sinter to the chip bonding area. Due to the limitations of the pre-coating process, there are also requirements for the size of the chip bonding area, and it is also not suitable for smaller bonding areas. At the same time, due to the requirements of the characteristics of the pre-coated metal film, after the pre-coating of the metal film, it is necessary to cover the exposed side of the metal film with a protective film to prevent the metal film from being damaged or oxidized during the transfer process. This causes the problem of metal film damage and inconvenience in operation during the subsequent film removal process. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for copper coating in a wafer bonding area, which can improve chip yield, reliability and stability.

[0005] According to the technical solution provided by the present invention, the method for copper coating the wafer bonding area comprises the following steps: S1. Clean the wafer to be copper-clad. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer to form a bonding area and a non-bonding area on the front of the wafer. The material of the metal layer is gold or silver, and the thickness of the metal layer is 1-10kA. S2, providing a copper sheet for copper cladding, wherein the back side of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and a first protective film is attached to the front side of the copper sheet; S3, preparing a metal bonding slurry and transferring the slurry to the bonding area of ​​the wafer; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material, the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within a distance that causes a short circuit in the bonding area of ​​the wafer; S5, sintering the wafer covered with the copper sheet; S6, evenly filling the epoxy resin material between the non-bonding area on the front side of the wafer and the groove between the copper sheet and performing plastic sealing; S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components according to the cutting paths of the wafer; S8. Dry and separate the chip assembly, the chip assembly comprising a copper sheet, a chip, a slurry block and an epoxy resin sealant, the front side of the chip is connected to the back side of the slurry block, the front side of the slurry block is connected to the back side of the copper sheet, and the epoxy resin sealant seals the gaps between the chip and the slurry block and between the slurry block and the copper sheet.

[0006] Preferably, step S3 is specifically as follows: S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-95%, the particle size of the metal powder is 10nm-100μm, the metal powder includes one of silver, copper, palladium, rhodium, nickel or a mixture thereof, and the suspending agent includes ethylene glycol, tridecanol, halogenated alcohol or dibasic fat; S312, transferring the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying or screen printing, and controlling the coating thickness of the wet slurry to be 10 μm-100 μm; S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, the semi-curing baking temperature is controlled at 100-180°C, the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500ppm. After the semi-curing baking is completed, the wet slurry forms a wet slurry block.

[0007] Preferably, step S3 is specifically as follows: S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is a mixture of metal powder and a protective agent, the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10nm-100μm, the metal powder includes silver or copper, and the protective agent is amide or ethylenediamine; S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller; S323, using a reverse mold jig, the dry slurry corresponding to the non-bonding area on the front side of the wafer is removed from the transfer film to obtain a dry slurry block; or, the dry slurry on the non-bonding area on the front side of the wafer is cut off by laser etching to obtain a dry slurry block; S324. Accurately align the transfer film and the wafer bonding area through the positioning holes on the transfer film, transfer the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170°C and a pressure of 1-15MPa for a single dry slurry block. After the transfer is completed, peel off the transfer film.

[0008] Preferably, step S5 is specifically as follows: S511. Cover the first protective film with a second protective film, transfer the wafer covered with the copper sheet and the sintering jig into the sintering machine together, press the second protective film with the sintering press head, introduce protective gas through the air inlet on the sintering jig, perform pressure sintering, and evacuate the air during the sintering process or after the sintering is completed through the exhaust port on the sintering jig; the material of the second protective film is polytetrafluoroethylene, and the thickness of the second protective film is 10μm-200μm; during pressure sintering, the pressure of the sintering press head pressing the protective film is controlled at 3-30MPa, the sintering temperature is controlled at 200-300℃, and the sintering time is controlled at 30-120s.

[0009] S512, after sintering is completed, the temperature is slowly lowered, and after the slow cooling is completed, the second protective film is removed.

[0010] Preferably, step S5 is specifically as follows: S521. Transfer the copper-covered wafer and the sintering jig into an oven together, introduce protective gas through the air inlet of the oven to perform pressure-free sintering, and evacuate the oven through the exhaust port during or after the sintering process. During pressure-free sintering, the baking temperature is controlled at 150-300°C and the baking time is controlled at 30-90 minutes.

[0011] S522, slowly cool down after sintering is completed.

[0012] Preferably, step S6 is specifically as follows: S611. Transfer the wafer with the copper sheet sintered to the compression molding mold, evenly fill the epoxy resin material in the groove between the non-bonding area on the front side of the wafer and the copper sheet, cover the first protective film with a layer of third protective film, and attach the pressing head of the compression molding mold to the third protective film. Complete compression molding in the compression molding mold, and control the compression molding temperature at 150-250°C, the time at 10-100s, and the pressure at 10-60MPa. The material of the third protective film is PVC or PTFE, and the thickness of the third protective film is 10μm-150μm.

[0013] S612. After the compression molding is completed, the third protective film is removed, and the overflow glue on the copper sheet is cleaned by mechanical grinding or laser.

[0014] Preferably, step S6 is specifically as follows: S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the injection mold to a first protective film; S622, after the injection mold is pressed, the epoxy resin sealing material is injected into the groove between the non-bonding area on the front side of the wafer and the copper sheet through a press, and the injection temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa; S623. After the injection molding is completed, use mechanical grinding or laser to clean the overflow glue on the copper sheet.

[0015] Preferably, in step S2, the thickness of the copper sheet is 100 μm-1000 μm, and the distance between the front side of the copper sheet and the bottom of the groove is 10 μm-50 μm, and the spacing between the copper sheets in adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas.

[0016] Preferably, in step S2, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC.

[0017] Preferably, in step S7, the wafer is separated into independent chips by mechanical separation or laser separation according to the dicing lines of the wafer.

[0018] The present invention has the following advantages: 1. The metal bonding slurry (including wet slurry and dry slurry) provided by the present invention is suitable for wafers of different bonding sizes, which solves the limitation of the bonding size requirements of the prior art; 2. The present invention provides a wafer-level copper plating process, which improves the copper plating efficiency and accuracy; 3. The present invention can coat copper on different wafer bonding areas through the design of copper sheets, thus avoiding the limitation of the traditional copper coating process that has strict requirements on the bonding area; 4. The present invention greatly improves the chip separation yield and chip reliability through the epoxy resin filling material process; 5. The chip protection structure formed by the process of the present invention avoids the high cost and easy cracking of traditional polyimide, and improves the chip yield and reliability; 6. The present invention provides a practical chip copper coating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a stereoscopic diagram of the chip components obtained in Example 1, Example 4, Example 5 and Example 8.

[0020] Figure 2 It is a cross-sectional view of the chip components obtained in Example 1, Example 4, Example 5 and Example 8.

[0021] Figure 3 It is a stereoscopic diagram of the chip components obtained in Example 2, Example 3, Example 6 and Example 7.

[0022] Figure 4 It is a cross-sectional view of the chip components obtained in Example 2, Example 3, Example 6 and Example 7. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0024] Example 1 A method for copper coating a wafer bonding area, the method comprising the following steps: S1. Clean the wafers that need to be copper-clad, and remove organic matter, oxides or other impurities that affect the copper-clad process in the previous process. After cleaning, dry the wafers. After drying, sputter a metal layer on the front side of the wafer. The metal layer is made of gold or silver, which helps to improve the bonding stability and reliability. The thickness of the metal layer is 1-10kA, forming a bonding area and a non-bonding area on the front side of the wafer. S2, providing a copper sheet 1 for copper cladding, the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm, and a first protective film is attached to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC; S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-90%, the particle size of the metal powder is 10nm-100μm, the metal powder includes one of silver, copper, palladium, rhodium, nickel or a mixture thereof, and the suspending agent includes ethylene glycol, tridecanol, halogenated alcohol or dibasic fat; S312, transfer the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying or screen printing. If the bonding area is smaller than 1mm×1mm, it is recommended to select dispensing or spraying. If the bonding area is larger than 1mm×1mm, it is recommended to select dispensing or screen printing. The coating thickness of the wet slurry is controlled within 10μm-100μm. S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, wherein the semi-curing baking temperature is controlled at 100-180° C., the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500 ppm to avoid oxidation or over-reaction of the slurry, which may affect the subsequent sintering quality. After the semi-curing baking is completed, the wet slurry forms a wet slurry block 31; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material (such as butyral rubber), the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within the distance that causes the bonding area of ​​the wafer to short-circuit, and generally the distance between the copper sheets of adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas; S511, a second protective film is covered on the first protective film, the wafer covered with the copper sheet and the sintering fixture are transferred to the sintering machine together, the sintering pressure head presses the second protective film, the material of the second protective film is polytetrafluoroethylene, the thickness of the second protective film is 10μm-200μm, and the protective gas is introduced through the air inlet on the sintering fixture to perform pressure sintering. During pressure sintering, the pressure of the sintering pressure head pressing the protective film is controlled at 3-30MPa, the sintering temperature is controlled at 200-300℃, and the sintering time is controlled at 30-120s. The exhaust port on the sintering fixture is used to evacuate during the sintering process or after the sintering is completed; S512, slowly cooling down after sintering is completed, and removing the second protective film after the slow cooling down is completed; S611, transferring the wafer after sintering the copper sheet to a compression mold, covering the first protective film with a third protective film to prevent the epoxy resin material from adhering to the pressure head of the compression mold, the third protective film is made of PVC or PTFE, and the thickness of the third protective film is 10 μm-150 μm, the pressure head of the compression mold is attached to the third protective film, and the epoxy resin material is evenly filled in the groove between the non-bonding area on the front side of the wafer and the copper sheet, and compression molding is completed in the compression mold, the compression molding temperature is controlled at 150-250°C, the time is 10-100s, and the pressure is 10-60MPa, and the epoxy resin material forms epoxy resin sealant 4; S612, after the compression molding is completed, the third protective film is removed, and the overflow glue on the copper sheet is cleaned by mechanical grinding or laser; S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the cutting path of the wafer; S8, drying the separated chip assembly, the chip assembly comprising the copper sheet 1, the chip 2, the wet slurry block 31 and the epoxy resin sealant 4, the front of the chip 2 is connected to the back of the wet slurry block 31, the front of the wet slurry block 31 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the wet slurry block 31 and the gap between the wet slurry block 31 and the copper sheet 1, as shown in FIG. Figure 1 , Figure 2 shown.

[0025] Example 2 A method for copper coating a wafer bonding area, the method comprising the following steps: S1. Clean the wafers that need to be copper-clad, and remove organic matter, oxides or other impurities that affect the copper-clad process in the previous process. After cleaning, dry the wafers. After drying, sputter a metal layer on the front side of the wafer. The metal layer is made of gold or silver, which helps to improve the bonding stability and reliability. The thickness of the metal layer is 1-10kA, forming a bonding area and a non-bonding area on the front side of the wafer. S2, providing a copper sheet 1 for copper cladding, the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm, and a first protective film is attached to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC; S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is a mixture of metal powder and a protective agent, the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10nm-100μm, the metal powder includes silver or copper, and the protective agent is amide or ethylenediamine; S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller; S323, using a reverse mold jig, the dry slurry corresponding to the non-bonding area on the front side of the wafer is removed from the transfer film to obtain a dry slurry block; or, the dry slurry on the non-bonding area on the front side of the wafer is cut off by laser etching to obtain a dry slurry block 32; S324, accurately aligning the transfer film and the wafer bonding area through the positioning holes on the transfer film, transferring the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170° C. and a pressure of 1-15 MPa on a single dry slurry block, and after the transfer is completed, peeling off the transfer film; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material (such as butyral rubber), the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within the distance that causes the bonding area of ​​the wafer to short-circuit, and generally the distance between the copper sheets of adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas; S521, transferring the wafer covered with the copper sheet and the sintering fixture into an oven, introducing protective gas through the air inlet of the oven, and performing pressure-free sintering. During pressure-free sintering, the baking temperature is controlled at 150-300° C., and the baking time is controlled at 30-90 minutes. Vacuuming is performed through the exhaust port of the oven during the sintering process or after the sintering is completed; S522, slowly cooling down after sintering is completed; S611, transferring the wafer after sintering the copper sheet to the compression mold, uniformly filling the epoxy resin material in the groove between the non-bonding area on the front side of the wafer and the copper sheet, covering the first protective film with a third protective film to prevent the epoxy resin material from adhering to the pressing head of the compression mold, the material of the third protective film is PVC or PTFE, the thickness of the third protective film is 10μm-150μm, the pressing head of the compression mold is attached to the third protective film, and compression molding is completed in the compression mold, and the compression molding temperature is controlled at 150-250℃, the time is 10-100s, and the pressure is 10-60MPa to form epoxy resin sealant 4; S612, after the compression molding is completed, the third protective film is removed, and the overflow glue on the copper sheet is cleaned by mechanical grinding or laser; S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the cutting path of the wafer; S8, drying and separating the chip assembly, the chip assembly includes the copper sheet 1, the chip 2, the dry slurry block 32 and the epoxy resin sealant 4, the front of the chip 2 is connected to the back of the dry slurry block 32, the front of the dry slurry block 32 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the dry slurry block 32 and the gap between the dry slurry block 32 and the copper sheet 1, as shown in FIG. Figure 3 , Figure 4 shown.

[0026] Example 3 A method for copper coating a wafer bonding area, the method comprising the following steps: S1. Clean the wafers that need to be copper-clad, and remove organic matter, oxides or other impurities that affect the copper-clad process in the previous process. After cleaning, dry the wafers. After drying, sputter a metal layer on the front side of the wafer. The metal layer is made of gold or silver, which helps to improve the bonding stability and reliability. The thickness of the metal layer is 1-10kA, forming a bonding area and a non-bonding area on the front side of the wafer. S2, providing a copper sheet 1 for copper cladding, the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm, and a first protective film is attached to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC; S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is a mixture of metal powder and a protective agent, the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10nm-100μm, the metal powder includes silver or copper, and the protective agent is amide or ethylenediamine; S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller; S323, using a reverse mold jig, the dry slurry corresponding to the non-bonding area on the front side of the wafer is removed from the transfer film to obtain a dry slurry block; or, the dry slurry on the non-bonding area on the front side of the wafer is cut off by laser etching to obtain a dry slurry block 32; S324, accurately aligning the transfer film and the wafer bonding area through the positioning holes on the transfer film, transferring the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170° C. and a pressure of 1-15 MPa on a single dry slurry block, and after the transfer is completed, peeling off the transfer film; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material (such as butyral rubber), the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within the distance that causes the bonding area of ​​the wafer to short-circuit, and generally the distance between the copper sheets of adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas; S511, a second protective film is covered on the first protective film, the wafer covered with the copper sheet and the sintering fixture are transferred to the sintering machine together, the sintering pressure head presses the second protective film, the material of the second protective film is polytetrafluoroethylene, the thickness of the second protective film is 10μm-200μm, and the protective gas is introduced through the air inlet on the sintering fixture to perform pressure sintering. During pressure sintering, the pressure of the sintering pressure head pressing the protective film is controlled at 3-30MPa, the sintering temperature is controlled at 200-300℃, and the sintering time is controlled at 30-120s. The exhaust port on the sintering fixture is used to evacuate during the sintering process or after the sintering is completed; S512, after sintering is completed, the temperature is slowly lowered, and after the slow cooling is completed, the second protective film is removed.

[0027] S611, transferring the wafer after sintering the copper sheet to the compression mold, uniformly filling the epoxy resin material in the groove between the non-bonding area on the front side of the wafer and the copper sheet, covering the first protective film with a third protective film to prevent the epoxy resin material from adhering to the pressing head of the compression mold, the material of the third protective film is PVC or PTFE, the thickness of the third protective film is 10μm-150μm, the pressing head of the compression mold is attached to the third protective film, and compression molding is completed in the compression mold, the compression molding temperature is controlled at 150-250℃, the time is 10-100s, and the pressure is 10-60MPa, and the epoxy resin material forms epoxy resin sealant 4; S612, after the compression molding is completed, the third protective film is removed, and the overflow glue on the copper sheet is cleaned by mechanical grinding or laser; S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the cutting path of the wafer; S8, drying and separating the chip assembly, the chip assembly includes the copper sheet 1, the chip 2, the dry slurry block 32 and the epoxy resin sealant 4, the front of the chip 2 is connected to the back of the dry slurry block 32, the front of the dry slurry block 32 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the dry slurry block 32 and the gap between the dry slurry block 32 and the copper sheet 1, as shown in FIG. Figure 3 , Figure 4 shown.

[0028] Example 4 A method for copper coating a wafer bonding area, the method comprising the following steps: S1. Clean the wafers that need to be copper-clad, and remove organic matter, oxides or other impurities that affect the copper-clad process in the previous process. After cleaning, dry the wafers. After drying, sputter a metal layer on the front side of the wafer. The metal layer is made of gold or silver, which helps to improve the bonding stability and reliability. The thickness of the metal layer is 1-10kA, forming a bonding area and a non-bonding area on the front side of the wafer. S2, providing a copper sheet 1 for copper cladding, the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm, and a first protective film is attached to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC; S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-90%, the particle size of the metal powder is 10nm-100μm, the metal powder includes one of silver, copper, palladium, rhodium, nickel or a mixture thereof, and the suspending agent includes ethylene glycol, tridecanol, halogenated alcohol or dibasic fat; S312, transfer the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying or screen printing. If the bonding area is smaller than 1mm×1mm, it is recommended to select dispensing or spraying. If the bonding area is larger than 1mm×1mm, it is recommended to select dispensing or screen printing. The coating thickness of the wet slurry is controlled within 10μm-100μm. S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, wherein the semi-curing baking temperature is controlled at 100-180° C., the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500 ppm to avoid oxidation or over-reaction of the slurry, which may affect the subsequent sintering quality. After the semi-curing baking is completed, the wet slurry forms a wet slurry block 31; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material (such as butyral rubber), the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within the distance that causes the bonding area of ​​the wafer to short-circuit, and generally the distance between the copper sheets of adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas; S521, transferring the wafer covered with the copper sheet and the sintering fixture into an oven, introducing protective gas through the air inlet of the oven, and performing pressure-free sintering. During pressure-free sintering, the baking temperature is controlled at 150-300° C., and the baking time is controlled at 30-90 minutes. Vacuuming is performed through the exhaust port of the oven during the sintering process or after the sintering is completed; S522, slowly cooling down after sintering is completed; S611, transferring the wafer after sintering the copper sheet to the compression mold, uniformly filling the epoxy resin material in the groove between the non-bonding area on the front side of the wafer and the copper sheet, covering the first protective film with a third protective film to prevent the epoxy resin material from adhering to the pressing head of the compression mold, the material of the third protective film is PVC or PTFE, the thickness of the third protective film is 10μm-150μm, the pressing head of the compression mold is attached to the third protective film, and compression molding is completed in the compression mold, the compression molding temperature is controlled at 150-250℃, the time is 10-100s, and the pressure is 10-60MPa, and the epoxy resin material forms epoxy resin sealant 4; S612, after the compression molding is completed, the third protective film is removed, and the overflow glue on the copper sheet is cleaned by mechanical grinding or laser; S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the cutting path of the wafer; S8, drying the separated chip assembly, the chip assembly comprising the copper sheet 1, the chip 2, the wet slurry block 31 and the epoxy resin sealant 4, the front of the chip 2 is connected to the back of the wet slurry block 31, the front of the wet slurry block 31 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the wet slurry block 31 and the gap between the wet slurry block 31 and the copper sheet 1, as shown in FIG. Figure 1 , Figure 2 shown.

[0029] Example 5 A method for copper coating a wafer bonding area, the method comprising the following steps: S1. Clean the wafers that need to be copper-clad, and remove organic matter, oxides or other impurities that affect the copper-clad process in the previous process. After cleaning, dry the wafers. After drying, sputter a metal layer on the front side of the wafer. The metal layer is made of gold or silver, which helps to improve the bonding stability and reliability. The thickness of the metal layer is 1-10kA, forming a bonding area and a non-bonding area on the front side of the wafer. S2, providing a copper sheet 1 for copper cladding, the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm, and a first protective film is attached to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC; S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-90%, the particle size of the metal powder is 10nm-100μm, the metal powder includes one of silver, copper, palladium, rhodium, nickel or a mixture thereof, and the suspending agent includes ethylene glycol, tridecanol, halogenated alcohol or dibasic fat; S312, transfer the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying or screen printing. If the bonding area is smaller than 1mm×1mm, it is recommended to select dispensing or spraying. If the bonding area is larger than 1mm×1mm, it is recommended to select dispensing or screen printing. The coating thickness of the wet slurry is controlled within 10μm-100μm. S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, wherein the semi-curing baking temperature is controlled at 100-180° C., the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500 ppm to avoid oxidation or over-reaction of the slurry, which may affect the subsequent sintering quality. After the semi-curing baking is completed, the wet slurry forms a wet slurry block 31; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material (such as butyral rubber), the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within the distance that causes the bonding area of ​​the wafer to short-circuit, and generally the distance between the copper sheets of adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas; S511, a second protective film is covered on the first protective film, the wafer covered with the copper sheet and the sintering fixture are transferred to the sintering machine together, the sintering pressure head presses the second protective film, the material of the second protective film is polytetrafluoroethylene, the thickness of the second protective film is 10μm-200μm, and the protective gas is introduced through the air inlet on the sintering fixture to perform pressure sintering. During pressure sintering, the pressure of the sintering pressure head pressing the protective film is controlled at 3-30MPa, the sintering temperature is controlled at 200-300℃, and the sintering time is controlled at 30-120s. The exhaust port on the sintering fixture is used to evacuate during the sintering process or after the sintering is completed; S512, slowly cooling down after sintering is completed, and removing the second protective film after the slow cooling down is completed; S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the injection mold to a first protective film; S622, after the injection mold is pressed, the epoxy resin sealing material is injected into the groove between the non-bonding area on the front side of the wafer and the back side of the copper sheet through a press, the injection temperature is controlled at 150-250° C., the time is 10-100 s, and the pressure is 10-60 MPa, and the epoxy resin material forms epoxy resin sealing material 4; S623. After the injection molding is completed, the excess glue on the copper sheet is cleaned by mechanical grinding or laser. S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the cutting path of the wafer; S8, drying the separated chip assembly, the chip assembly comprising the copper sheet 1, the chip 2, the wet slurry block 31 and the epoxy resin sealant 4, the front of the chip 2 is connected to the back of the wet slurry block 31, the front of the wet slurry block 31 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the wet slurry block 31 and the gap between the wet slurry block 31 and the copper sheet 1, as shown in FIG. Figure 1 , Figure 2 shown.

[0030] Example 6 A method for copper coating a wafer bonding area, the method comprising the following steps: S1. Clean the wafers that need to be copper-clad, and remove organic matter, oxides or other impurities that affect the copper-clad process in the previous process. After cleaning, dry the wafers. After drying, sputter a metal layer on the front side of the wafer. The metal layer is made of gold or silver, which helps to improve the bonding stability and reliability. The thickness of the metal layer is 1-10kA, forming a bonding area and a non-bonding area on the front side of the wafer. S2, providing a copper sheet 1 for copper cladding, the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm, and a first protective film is attached to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC; S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is a mixture of metal powder and a protective agent, the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10nm-100μm, the metal powder includes silver or copper, and the protective agent is amide or ethylenediamine; S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller; S323, using a reverse mold jig, the dry slurry corresponding to the non-bonding area on the front side of the wafer is removed from the transfer film to obtain a dry slurry block; or, the dry slurry on the non-bonding area on the front side of the wafer is cut off by laser etching to obtain a dry slurry block 32; S324, accurately aligning the transfer film and the wafer bonding area through the positioning holes on the transfer film, transferring the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170° C. and a pressure of 1-15 MPa on a single dry slurry block, and after the transfer is completed, peeling off the transfer film; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material (such as butyral rubber), the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within the distance that causes the bonding area of ​​the wafer to short-circuit, and generally the distance between the copper sheets of adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas; S521, transferring the wafer covered with the copper sheet and the sintering fixture into an oven, introducing protective gas through the air inlet of the oven, and performing pressure-free sintering. During pressure-free sintering, the baking temperature is controlled at 150-300° C., and the baking time is controlled at 30-90 minutes. Vacuuming is performed through the exhaust port of the oven during the sintering process or after the sintering is completed; S522, slowly cooling down after sintering is completed; S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the injection mold to a first protective film; S622, after the injection mold is pressed, the epoxy resin sealing material is injected into the groove between the non-bonding area on the front side of the wafer and the back side of the copper sheet through a press, the injection temperature is controlled at 150-250° C., the time is 10-100 s, and the pressure is 10-60 MPa, and the epoxy resin material forms epoxy resin sealing material 4; S623. After the injection molding is completed, the excess glue on the copper sheet is cleaned by mechanical grinding or laser. S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the cutting path of the wafer; S8, drying and separating the chip assembly, the chip assembly includes the copper sheet 1, the chip 2, the dry slurry block 32 and the epoxy resin sealant 4, the front of the chip 2 is connected to the back of the dry slurry block 32, the front of the dry slurry block 32 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the dry slurry block 32 and the gap between the dry slurry block 32 and the copper sheet 1, as shown in FIG. Figure 3 , Figure 4 shown.

[0031] Example 7 A method for copper coating a wafer bonding area, the method comprising the following steps: S1. Clean the wafers that need to be copper-clad, and remove organic matter, oxides or other impurities that affect the copper-clad process in the previous process. After cleaning, dry the wafers. After drying, sputter a metal layer on the front side of the wafer. The metal layer is made of gold or silver, which helps to improve the bonding stability and reliability. The thickness of the metal layer is 1-10kA, forming a bonding area and a non-bonding area on the front side of the wafer. S2, providing a copper sheet 1 for copper cladding, the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm, and a first protective film is attached to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC; S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is a mixture of metal powder and a protective agent, the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10nm-100μm, the metal powder includes silver or copper, and the protective agent is amide or ethylenediamine; S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller; S323, using a reverse mold jig, the dry slurry corresponding to the non-bonding area on the front side of the wafer is removed from the transfer film to obtain a dry slurry block; or, the dry slurry on the non-bonding area on the front side of the wafer is cut off by laser etching to obtain a dry slurry block 32; S324, accurately aligning the transfer film and the wafer bonding area through the positioning holes on the transfer film, transferring the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170° C. and a pressure of 1-15 MPa on a single dry slurry block, and after the transfer is completed, peeling off the transfer film; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material (such as butyral rubber), the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within the distance that causes the bonding area of ​​the wafer to short-circuit, and generally the distance between the copper sheets of adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas; S511, a second protective film is covered on the first protective film, the wafer covered with the copper sheet and the sintering fixture are transferred to the sintering machine together, the sintering pressure head presses the second protective film, the material of the second protective film is polytetrafluoroethylene, the thickness of the second protective film is 10μm-200μm, and the protective gas is introduced through the air inlet on the sintering fixture to perform pressure sintering. During pressure sintering, the pressure of the sintering pressure head pressing the protective film is controlled at 3-30MPa, the sintering temperature is controlled at 200-300℃, and the sintering time is controlled at 30-120s. The exhaust port on the sintering fixture is used to evacuate during the sintering process or after the sintering is completed; S512, slowly cooling down after sintering is completed, and removing the second protective film after the slow cooling down is completed; S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the injection mold to a first protective film; S622, after the injection mold is pressed, the epoxy resin sealing material is injected into the groove between the non-bonding area on the front side of the wafer and the back side of the copper sheet through a press, the injection temperature is controlled at 150-250° C., the time is 10-100 s, and the pressure is 10-60 MPa, and the epoxy resin material forms epoxy resin sealing material 4; S623. After the injection molding is completed, the excess glue on the copper sheet is cleaned by mechanical grinding or laser. S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the cutting path of the wafer; S8, drying and separating the chip assembly, the chip assembly includes the copper sheet 1, the chip 2, the dry slurry block 32 and the epoxy resin sealant 4, the front of the chip 2 is connected to the back of the dry slurry block 32, the front of the dry slurry block 32 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the dry slurry block 32 and the gap between the dry slurry block 32 and the copper sheet 1, as shown in FIG. Figure 3 , Figure 4 shown.

[0032] Example 8 A method for copper coating a wafer bonding area, the method comprising the following steps: S1. Clean the wafers that need to be copper-clad, and remove organic matter, oxides or other impurities that affect the copper-clad process in the previous process. After cleaning, dry the wafers. After drying, sputter a metal layer on the front side of the wafer. The metal layer is made of gold or silver, which helps to improve the bonding stability and reliability. The thickness of the metal layer is 1-10kA, forming a bonding area and a non-bonding area on the front side of the wafer. S2. Provide a copper sheet for copper cladding, the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm, and a first protective film is attached to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC; S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-90%, the particle size of the metal powder is 10nm-100μm, the metal powder includes one of silver, copper, palladium, rhodium, nickel or a mixture thereof, and the suspending agent includes ethylene glycol, tridecanol, halogenated alcohol or dibasic fat; S312, transfer the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying or screen printing. If the bonding area is smaller than 1mm×1mm, it is recommended to select dispensing or spraying. If the bonding area is larger than 1mm×1mm, it is recommended to select dispensing or screen printing. The coating thickness of the wet slurry is controlled within 10μm-100μm. S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, wherein the semi-curing baking temperature is controlled at 100-180° C., the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500 ppm to avoid oxidation or over-reaction of the slurry, which may affect the subsequent sintering quality. After the semi-curing baking is completed, the wet slurry forms a wet slurry block 31; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material (such as butyral rubber), the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within the distance that causes the bonding area of ​​the wafer to short-circuit, and generally the distance between the copper sheets of adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas; S521, transferring the wafer covered with the copper sheet and the sintering fixture into an oven, introducing protective gas through the air inlet of the oven, and performing pressure-free sintering. During pressure-free sintering, the baking temperature is controlled at 150-300° C., and the baking time is controlled at 30-90 minutes. Vacuuming is performed through the exhaust port of the oven during the sintering process or after the sintering is completed; S522, slowly cooling down after sintering is completed; S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the injection mold to a first protective film; S622, after the injection mold is pressed, the epoxy resin sealing material is injected into the groove between the non-bonding area on the front side of the wafer and the back side of the copper sheet through a press, the injection temperature is controlled at 150-250° C., the time is 10-100 s, and the pressure is 10-60 MPa, and the epoxy resin material forms epoxy resin sealing material 4; S623. After the injection molding is completed, the excess glue on the copper sheet is cleaned by mechanical grinding or laser. S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the cutting path of the wafer; S8, drying the separated chip assembly, the chip assembly comprising the copper sheet 1, the chip 2, the wet slurry block 31 and the epoxy resin sealant 4, the front of the chip 2 is connected to the back of the wet slurry block 31, the front of the wet slurry block 31 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the wet slurry block 31 and the gap between the wet slurry block 31 and the copper sheet 1, as shown in FIG. Figure 1 , Figure 2 shown.

[0033] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for copper coating in a wafer bonding area, characterized in that The method comprises the following steps: S1. Clean the wafer to be copper-clad. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer to form a bonding area and a non-bonding area on the front of the wafer. The material of the metal layer is gold or silver, and the thickness of the metal layer is 1-10kA. S2, providing a copper sheet for copper cladding, wherein the back side of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and a first protective film is attached to the front side of the copper sheet; S3, preparing a metal bonding slurry and transferring the slurry to the bonding area of ​​the wafer; S4, transferring the wafer after the slurry transfer to a sintering jig, the bottom of the sintering jig is covered with a supporting soft material, the sintering jig is designed with an air inlet and an exhaust port, the copper sheet of step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark, the bonding area of ​​the copper sheet is attached to the front side of the slurry, and the distance between the copper sheets of adjacent bonding areas of the wafer is controlled within a distance that causes a short circuit in the bonding area of ​​the wafer; S5, sintering the wafer covered with the copper sheet; S6, evenly filling the epoxy resin material between the non-bonding area on the front side of the wafer and the groove between the copper sheet and performing plastic sealing; S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components according to the cutting paths of the wafer; S8. Dry and separate the chip assembly, the chip assembly comprising a copper sheet, a chip, a slurry block and an epoxy resin sealant, the front side of the chip is connected to the back side of the slurry block, the front side of the slurry block is connected to the back side of the copper sheet, and the epoxy resin sealant seals the gaps between the chip and the slurry block and between the slurry block and the copper sheet.

2. The method for copper coating in wafer bonding area according to claim 1, characterized in that: Step S3 is specifically as follows: S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-95%, the particle size of the metal powder is 10nm-100μm, the metal powder includes one of silver, copper, palladium, rhodium, nickel or a mixture thereof, and the suspending agent includes ethylene glycol, tridecanol, halogenated alcohol or dibasic fat; S312, transferring the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying or screen printing, and controlling the coating thickness of the wet slurry to be 10 μm-100 μm; S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, the semi-curing baking temperature is controlled at 100-180°C, the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500ppm. After the semi-curing baking is completed, the wet slurry forms a wet slurry block.

3. The method for copper coating in wafer bonding area according to claim 1, characterized in that: Step S3 is specifically as follows: S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is a mixture of metal powder and a protective agent, the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10nm-100μm, the metal powder includes silver or copper, and the protective agent is amide or ethylenediamine; S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller; S323, using a reverse mold jig, the dry slurry corresponding to the non-bonding area on the front side of the wafer is removed from the transfer film to obtain a dry slurry block; or, the dry slurry on the non-bonding area on the front side of the wafer is cut off by laser etching to obtain a dry slurry block; S324. Accurately align the transfer film and the wafer bonding area through the positioning holes on the transfer film, transfer the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170°C and a pressure of 1-15MPa for a single dry slurry block. After the transfer is completed, peel off the transfer film.

4. The method for copper coating in wafer bonding area according to claim 1, characterized in that: Step S5 is specifically as follows: S511, a second protective film is covered on the first protective film, the wafer covered with the copper sheet and the sintering jig are transferred to the sintering machine together, the sintering pressure head presses the second protective film, and the protective gas is introduced through the air inlet on the sintering jig to perform pressure sintering, and vacuum is evacuated during the sintering process or after the sintering is completed through the exhaust port on the sintering jig; the material of the second protective film is polytetrafluoroethylene, and the thickness of the second protective film is 10μm-200μm; during pressure sintering, the pressure of the sintering pressure head pressing the protective film is controlled at 3-30MPa, the sintering temperature is controlled at 200-300℃, and the sintering time is controlled at 30-120s; S512, after sintering is completed, the temperature is slowly lowered, and after the slow cooling is completed, the second protective film is removed.

5. The method for copper coating in wafer bonding area according to claim 1, characterized in that: Step S5 is specifically as follows: S521, transfer the copper-covered wafer and the sintering jig into an oven, introduce protective gas through the air inlet of the oven, perform pressure-free sintering, and evacuate the oven through the exhaust port during or after the sintering process; during pressure-free sintering, the baking temperature is controlled at 150-300° C. and the baking time is controlled at 30-90 minutes; S522, slowly cool down after sintering is completed.

6. The method for copper coating in wafer bonding area according to claim 1, characterized in that: Step S6 is specifically as follows: S611, transfer the wafer after the copper sheet sintering to the compression molding mold, evenly fill the epoxy resin material in the groove between the non-bonding area on the front side of the wafer and the copper sheet, cover the first protective film with a third protective film, and the pressure head of the compression molding mold is attached to the third protective film, and complete the compression molding in the compression molding mold, and the compression molding temperature is controlled at 150-250°C, the time is 10-100s, and the pressure is 10-60MPa; the material of the third protective film is PVC or PTFE, and the thickness of the third protective film is 10μm-150μm; S612. After the compression molding is completed, the third protective film is removed, and the overflow glue on the copper sheet is cleaned by mechanical grinding or laser.

7. The method for copper coating in wafer bonding area according to claim 1, characterized in that: Step S6 is specifically as follows: S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the injection mold to a first protective film; S622, after the injection mold is pressed, the epoxy resin sealing material is injected into the groove between the non-bonding area on the front side of the wafer and the copper sheet through a press, and the injection temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa; S623. After the injection molding is completed, use mechanical grinding or laser to clean the overflow glue on the copper sheet.

8. The method for copper coating in wafer bonding area according to claim 1, characterized in that: In step S2, the thickness of the copper sheet is 100 μm-1000 μm, and the distance between the front surface of the copper sheet and the bottom of the groove is 10 μm-50 μm, and the distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be less than half of the distance between the two bonding areas.

9. The method for copper coating in wafer bonding area according to claim 1, characterized in that: In step S2, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC.

10. The method for copper coating in wafer bonding area according to claim 1, characterized in that: In step S7, the wafer is separated into independent chips by mechanical separation or laser separation according to the dicing lines of the wafer.

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